The present invention relates to fluid motors for use in the machine tool field. More particularly, the present invention relates to fluid motors which utilize a simple air driven toggle mechanism for activating the shot pin units.
Pneumatic piston and cylinder units are used in a great many different ways for many different functions in connection with the machine tool field. These functions include advancing and retracting tools of various types, advancing and retracting fixtures and the like, advancing and retracting work pieces, ejecting work pieces, work piece locating and work piece clamping, just to name a few. Often it is necessary for these pneumatic cylinder units to provide work functions at closely adjacent points on a work piece or machine. Because of the generally bulky configuration of these piston and cylinder units, it is often necessary in such cases to provide external linkages or levers extending from the piston rod to these closely adjacent points where the application of force is required. The existence of such external levers or other mechanisms presents not only a safety hazard, but it greatly complicates the apparatus necessary to accomplish a given function. In addition, the initial costs and the maintenance costs involved with this complex system are excessive. A good example of where it is often necessary to apply a force on closely spaced centers is in the automobile industry where sheet metal parts need to be precisely located while the parts are assembled, usually by welding.
Prior art devices which are narrow and do not sacrifice output force capacity have been developed. These devices include a rotationally oscillating piston located within a generally sector-shaped chamber, a reciprocating ram element for performing work, internal linkage means interconnecting the ram element and the piston, and means for supplying a fluid under pressure to the chamber. The device is designed to allow the pressurized fluid to be supplied to opposite sides of the piston in order to actuate and de-actuate the piston.
While the prior art devices have performed satisfactorily in the machine tool industry, the continued development of these devices has been directed towards improving their function, their performance and their durability.
The present invention provides the art with a shot pin which includes a rotary oscillating piston located in a sector-shaped chamber, a reciprocating ram for performing work, and an internal linkage assembly interconnecting the piston and the ram. The shot pin of the present invention includes a mechanism for preventing unlocking of the shot pin from its extended position, a manual unlocking device, a rectangular ram, a hardened scraper and seals which protect the ram as well as numerous other improvement over the systems disclosed in the prior art.
Other advantages and objects of the present invention will become apparent to those skilled in the art from the subsequent detailed description, appended claims and drawings.